1. Field of the Invention
The present invention relates to a rear suspension apparatus for a motor vehicle.
2. Description of the Related Art
Japanese Patent Laid-Open No. 4-283114 discloses a conventional rear suspension apparatus for a motor vehicle in which, in a rear-wheel-drive vehicle, right- and left-hand trailing arms are connected to each other through a torsion beam extending in vehicle-width directions. In the rear suspension apparatus, while a rear differential gear case for covering a rear differential gear is located between rear right- and left-wheels because of the rear-wheel drive, in order to avoid the interference between the torsion beam and the rear differential gear case, in the aforesaid conventional art, a central portion of the torsion beam in the vehicle-width directions is protrusively curved upwardly, that is, the torsion beam is disposed to bypass the rear differential gear case upwardly.
Furthermore, in the case that a motor vehicle with a considerably short front nose recently called RV (Recreational Vehicle) or SUV (Sports Utility Vehicle) is designed as a rear-wheel-drive vehicle, a torsion beam type rear suspension apparatus is employed to lower a floor panel to the utmost.
On the other hand, for a motor vehicle, it is desired that the floor panel in a rear section of the vehicle body does not lower at collision from its rear side. That is, need exists that various kinds of parts such as a fuel tank placed under the floor panel in the vehicle body rear section do not come into contact with the road surface because of the lowering of the floor panel at the rear side collision. Particularly, in the case of the aforesaid RV, for example, since the distance between the rear wheels and the vehicle body rear end portion is short, there is a high possibility that a large external force works on the rear suspension at the rear side collision, and the external force at the rear side collision can deform the rear wheels upwardly with respect to the vehicle body, which results in a relative fall of the floor panel.
Accordingly, the present invention has been developed with a view to eliminating the above-mentioned problem, and it is an object of this invention to provide a rear suspension apparatus for a motor vehicle with a torsion beam, which is capable of preventing the fall of the vehicle hody during a rear side collision.
For eliminating the foregoing problem and achieving the purpose, according to a first aspect of this invention, in a rear suspension apparatus for a motor vehicle having a differential gear case disposed between rear right- and left-wheels, which rear suspension is of a torsion beam type, a central portion of the torsion beam in a vehicle width direction is bent to extend along a configuration of the differential gear case and is disposed at the rear of the differential gear case, and a suspension damper (absorber) stretched between the torsion beam and a vehicle body is disposed in a state of being inclined or tilted forwardly and upwardly (inclined to take a further forward position in accordance with advancing upwardly).
With the first aspect, when an external force from a rear side works on the torsion beam during a rear side collision, the suspension damper acts as a strut because of being an abrupt external force, and the inclination of the damper causes the torsion beam to shift (be displaced) downwardly, so that the rear wheels relatively move downwardly with respect to the vehicle body, thereby preventing the fall of the vehicle body rear section.
A second aspect is that, in a rear suspension apparatus for a motor vehicle having a differential gear case disposed between rear right- and left-wheels, wherein a central portion of a torsion beam in a width direction of said motor vehicle is bent along a configuration of said differential gear case, and is located at the rear of said differential gear case, and wherein said differential gear case has a curved section protruding rearwardly, and said central portion of said torsion beam is placed at a lower position than a peak portion of said curved section.
With the second aspect, when an external force from a rear side works on the torsion beam at the rear side collision, the torsion beam is brought into contact with the curved section of the rear differential gear case to be guided to shift downwardly, and the rear wheels shift downwardly relative to the vehicle body, which can prevent the fall of the body rear section.
A third aspect is that, in a rear suspension apparatus for a motor vehicle having a differential gear case disposed between rear right- and left-wheels, wherein a central portion of a torsion beam in a width direction of said motor vehicle is bent along a configuration of said differential gear case, and is located at the rear of said differential gear case, and wherein said central portion of said torsion beam is formed to be at a higher position than both end portions thereof in said vehicle width direction.
With the third aspect, when an external force from a rear side is applied to the torsion beam at the rear side collision, owing to the fact that the central portion is formed to be higher than both the end portions in the vehicle width direction, the torsion beam tends to more easily shift downwardly, and the rear wheels shift downwardly relative to the vehicle body, so that the fall of the vehicle body rear section is preventable.
A fourth aspect is that, in a rear suspension apparatus for a motor vehicle having a differential gear case disposed between rear right- and left-wheels, wherein said torsion beam is connected to said vehicle body through a lateral link extending in said vehicle width direction, and said lateral link is disposed to be inclined up and down in said vehicle width direction, with its upper end portion being connected to said vehicle body while its lower end portion being connected to said torsion beam.
With the fourth aspect, when an external force from a rear side acts on the lateral link and the torsion beam, since the lateral link is placed to be tilted up and down in the vehicle width direction, the torsion beam shifts downwardly and the rear wheels shift downwardly relative to the vehicle body, thus preventing the fall of the vehicle body rear section.
A fifth aspect is that, in a rear suspension apparatus for a motor vehicle having a differential gear case disposed between rear right- and left-wheels, wherein an exhaust pipe extending from an engine is bent for bypassing said torsion beam to pass above said torsion beam, and extends to a rear section of said vehicle body, and a portion of said exhaust pipe rearwardly extending from the curved portion is disposed to run from above said torsion beam to below said torsion beam to cross said torsion beam, and is inclined downwardly and rearwardly.
With the fifth aspect, while an external force from a rear side works on a portion of the exhaust pipe rearwardly extending from the bent portion at the rear side collision, since this portion is tilted downwardly and rearwardly, the torsion beam shifts downwardly through the exhaust pipe and the rear wheels shift downwardly relative to the vehicle body, so that the fall of the vehicle body rear section is preventable.
In addition, although the portion of the exhaust pipe rearwardly extending from the bent portion is bent in the vicinity of the bent portion, the deformation by this bending reduces the space between the torsion beam and the bent portion, so that the upward shifting of the torsion beam is more surely preventable.
A sixth aspect is that, in a rear suspension apparatus for a motor vehicle having a differential gear case disposed between rear right- and left-wheels, wherein a central portion of a torsion beam in a width direction of said motor vehicle is bent along a configuration of said differential gear case, and is located at the rear of said differential gear case, and wherein a recessed space formed to a floor panel of said vehicle body and enlarging protrusively and downwardly is placed at the rear of said torsion beam, and the height of a lower end portion of a front wall defining said recessed space is set to exceed the height of an upper end portion of said torsion beam.
With the sixth aspect, although an external force from a rear side presses the recessed space (or the floor panel forming the recessed space) forwardly at the rear side collision, since the height of the lower end portion of the front wall defining the recessed space is set to exceed the upper end portion of the torsion beam, the recessed space allows the torsion beam to shift downwardly so that the rear wheels shift downwardly relative to the vehicle body to prevent the fall of the vehicle body rear section.
A seventh aspect is that, in the motor vehicle rear suspension apparatus employing the sixth aspect, the front wall extends at least from above the torsion beam to under the torsion beam, and is inclined downwardly and rearwardly.
With the seventh aspect, since the front wall is formed to be tilted downwardly and rearwardly, a stronger operation to shift the torsion beam downwardly takes place, so that the effects of the sixth aspect are more certainly obtainable.
An eighth aspect is that, in the motor vehicle rear suspension apparatus employing the sixth aspect, the lateral link is placed between the front wall and the torsion beam.
With the eighth aspect, the operation of the lateral link in the sixth aspect can more certainly produce the effects of the sixth or seventh aspect.
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form apart thereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.